Following 9-11, the members-only lounges - most of which are located behind security checkpoints -- were deemed off-limits to any person without an airline ticket for travel that day.

However, the newly formed Transportation Security Administration is allowing airlines to open the clubs to members who have passed required security checks. The rule was eased about a month ago, according to airlines that have been quietly notifying members of the renewed access.

Such clubs have grown in popularity among business travelers, who use the facilities to work or rest while waiting for flights. Without the restrictions, travelers can again use club conference rooms for meetings even if guests are heading in separate directions or not flying at all.

Customers must show proof of membership plus government-issued photo identification to pass through security.